JPH04237569A - Welded joint efficiency lowering preventing method - Google Patents

Abstract

PURPOSE:To improve welded joint efficienc by putting a welding heat-affected zone where joint efficienc of base metals is lowered in metal for build up welding where its strength is not lowered. CONSTITUTION:A weld zone of single drums 1 which are materials to be welded is subjected to build up welding 7 in advance, then, a groove 8 is formed thereon and then, the heat-affected zone 6 of the weld zone is put in build up weld part 7 and subjected to TIG welding to form a weld metal part 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a decrease in the efficiency of a welded joint, which is suitable for preventing a decrease in the strength of a weld heat-affected zone of high-strength materials.

0002

[Prior Art] In a space rocket chamber, as shown in the front view of FIG. The shell 1 is produced by bending with rollers and longitudinal welding 4, and then using a press to correct distortions caused by solution heat treatment to improve the strength of the base metal and the welded portion. Next, these single shells 1 are sequentially circumferentially welded 3 to form a welded metal part 5 and a heat affected zone 6, and a cylinder with a length of 4 to 5 m is manufactured, but no solution heat treatment is performed.

[0003] This is because the solution temperature is as high as about 810 to 830°C, and the cylindrical chamber is large in diameter, thin, and long, so the chamber deforms greatly after heat treatment, making distortion correction impossible. This is because product dimensions cannot be guaranteed. Therefore, after welding, the circumferential weld 3 part is 480 ~
Manufactured using only 500℃ aging treatment.

Therefore, the hardness distribution in the cross section of the circumferential TIG welded part is as shown in FIG. Compared to No. 1 and Weld Metal Part No. 5, the hardness is significantly lower and the joint efficiency is poor. As a result, the welded parts are designed to be overly thick, which has a negative impact on economy, weight reduction, and reliability.

[0005]

[Problems to be Solved by the Invention] The present invention has been proposed in view of the above circumstances, and it is an object of the present invention to accommodate the heat-affected zone of the base material, which reduces the joint efficiency, in a built-up metal that does not reduce the strength of the joint. It is an object of the present invention to provide a method for preventing a decrease in welded joint efficiency, which can improve efficiency.

[0006]

[Means for Solving the Problems] In order to solve the problem, the present invention provides a method for overlaying a welded part of a material to be welded in advance, forming a groove in the overlaying welding part, and then overlaying the heat-affected zone of the welded part. It is characterized by TIG welding within the weld area.

[0007]

[Function] In the method for preventing reduction in welded joint efficiency of the present invention,
The heat-affected zone, which softens and decreases in strength during TIG welding, is present in the build-up weld metal, and by performing aging treatment after welding so that the heat-affected zone does not exist in the base metal of the welded material, the joint efficiency can be improved. improves.

[0008]

[Example] An example in which the method for preventing a decrease in efficiency of a welded joint according to the present invention is applied to a welded joint in a space rocket chamber will be explained with reference to the drawings. 2 is a diagram of the temperature distribution of the welded part, and FIG. 3 is a diagram of the hardness distribution of the welded part.

First, in FIG. 1(I), after overlay welding 7 in the circumferential direction of the single shell 1 with a material whose strength does not decrease even with aging treatment, the single shells 1 are each subjected to solution heat treatment to remove heat effects. This prevents softening and strength reduction of portion 6.

Next, in FIG. 1 (II), a groove 8 for circumferential welding is formed in the overlay weld 7 portion. The width W of the overlay weld 7 is determined according to the plate thickness and groove shape of the single shell 1, and as shown in Figure 1 (III), the weld metal part 5 is formed by circumferential TIG welding. In some cases, the heat affected zone 6 is dimensioned to fall within the range of the overlay weld 7.

[0011] The temperature distribution at each position of the welded part thus formed is shown in Figure 2, showing that softening,
The temperature Ac1 or higher of the heat-affected zone 6, which causes a decrease in strength, is within the temperature range of the overlay weld 7, where the strength does not decrease even with aging treatment alone without solution treatment. Further, the hardness distribution after aging of the circumferential TIG welded joint constructed in this way is shown in FIG. 3, and it can be seen that there is no softening in the heat affected zone 6 and that the joint has sufficient strength.

As described above, according to this method, the efficiency of welded joints is improved, the amount of welding material is reduced, and the economy, weight reduction, and reliability of the rocket are improved.

[0013]

[Effects of the Invention] In short, according to the present invention, after overlay welding is performed on the welded part of the workpiece in advance and a groove is formed in the overlay welded part, the heat affected zone of the welded part is inserted into the overlay welded part. By performing TIG welding in the welded joint, the heat-affected zone where the joint efficiency of the base metal decreases is contained within the overlay metal where the strength does not decrease, thereby obtaining a method for preventing a decrease in welded joint efficiency that can improve the joint efficiency. The present invention is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 shows the procedure for preventing efficiency decline in an embodiment in which the method for preventing decline in efficiency of welded joints of the present invention is applied to welded joints in space rocket chambers, in the order of steps (I), (II), (
It is a sectional view shown as III).

FIG. 2 is a diagram of temperature distribution in a welded part.

FIG. 3 is a diagram of hardness distribution of a welded part.

FIG. 4 shows a known space rocket chamber;
A) is a front view, (B) is a sectional view of section B in (A), and (C) is a diagram of the hardness distribution of the welded part.

[Explanation of symbols]

1 Single body 3 Circumferential welding 4 Longitudinal welding 5 Welded metal part 6 Heat affected zone 7 Overlay welding 8 Bevel

Claims (1)

[Claims] [Claim 1] After overlaying the welding part of the material to be welded in advance and forming a groove in the overlaying welding part, the heat-affected zone of the welding part is contained within the overlaying welding part and TIG welding is performed. A method for preventing a decrease in welded joint efficiency, which is characterized by: